Use of unmanned aerial systems (UAS), popularly known as drones, is proliferating, and drones are in widespread use by commercial operators and hobbyists in part because of their low cost to acquire and operate. Hobbyist drones typically operate at low altitude, and Federal Aviation Administration (FAA) regulations require such drones fly only in line of sight of the hobbyist-operator. With their increasing use, hobbyist drones have been seen in situations where their presence creates a potential danger; one such situation is a wildfire where hobbyist drones have been observed operating in a restricted airspace created for firefighting aircraft. In addition, drones operated by commercial entities also could pose a danger if operated in or near the restricted airspace of a wildfire.
A popular hobbyist UAS configuration is a “quadcopter,” an example of which is the SZ DJI Technology Phantom 3 Pro drone. This UAS has a maximum unobstructed range from its controller of 3.1 miles and an altitude limit of 1,640 feet. The Pro 3 drone can fly at speeds up to 16 m/sec, has a duration of 23 minutes, and weighs about three pounds. See DGI P3 Pro User Guide V1.8, March 2016.
In 2015, wildfires in the United States burned more than 10 million acres. Wildfires occur in remote areas with little or no human habitation and in urban areas where wildfires may threaten homes and businesses. Wildfire suppression techniques include low-level aerial application of fire-retardant chemicals and water; such aerial application may be by fixed wing or rotary manned aircraft. To protect aircraft crews, local, state, and Federal regulations provide for a restricted airspace in wildfire areas, and if an unauthorized UAS is observed or otherwise detected in or near the restricted airspace established for a wildfire, air operations are suspended until the UAS no longer poses a risk.
Despite these regulations, incidents of UAS operating in the restricted airspace around wildfires is increasing. While no accidents have occurred, near misses with firefighting aircraft have. A U.S. Department of the Interior press release reports for 2015 more than 20 incidents of UAS encroaching on wildfires. Two of these incidents required evasive action by firefighting aircraft to avoid a collision. In twelve of the incidents, UAS adversely affected wildfire management and one incident led to a highway corridor shutdown. The U.S. Forest Service is addressing the issue through outreach efforts to educate the public while the FAA and local authorities rely on legislation, regulations, and awareness programs; however, to date, these efforts have not stopped unauthorized UAS operations in wildfire areas.
In addition to these and other direct Federal and local government efforts, government agencies have contracted with private companies such as UAS manufacturer SZ DJI Technology to limit unauthorized UAS operations. For example, under direction of the FAA, DJI Technology provided UAS control software to create geo-fences that display approved flight areas or that physically restrict UAS flight in a GPS-coordinated area. For this geo-fencing to be effective, UAS owners must responsibly update their UAS control software so that geo-fencing can be enforced. In another effort, the FAA now publishes restricted flight areas for emergency airspace through an FAA application (app) B4UFLY (www.faa.gov/uas/wheretofly/b4ufly/); however, the B4UFLY app does not provide any mechanism for enforcing these airspace restrictions. During the 2016 fire season, the U.S. Department of the Interior tested a prototype system based on this FAA approach. Even were all UAS operators to use the B4UFLY app, a gap will exist between the time a manufacturer receives and publishes the B4UFLY coordinates for a restricted area and the time a UAS operator updates the UAS software, so this approach does not provide enough assurance for emergency personnel responding to a rapidly changing wildfire.
Private companies also offer UAS detection and mitigation systems, which may use a variety of sensors including visual cameras, sound, and thermal sensors, but these systems generally are ineffective and inappropriate for fighting wildfires because of their static design. Typically, these systems are installed in a network around fixed sites such as stadiums, prisons, and private company campuses. The systems may detect UAS at these sites and notify on-site security personnel. While these systems provide the ability to detect an intruding UAS, such detection occurs only for a fixed area with static boundaries and the systems do not provide a solution for mitigating the threat posed by a UAS. Other systems provide mitigation by, for example, employing a frequency jammer that overpowers the signal between the UAS and the UAS controller, preventing the operator from maneuvering the UAS. However, jamming may create a dangerous situation in which a UAS may crash. Furthermore, in the United States, it is illegal for members of the public and local government agencies to jam radio signals without Federal Communication Commission (FCC) approval; thus, jamming to control or prevent unauthorized UAS operations usually is not an option for state and local governments in responding to wildfires.
In summary, wildfire incident response personnel cannot effectively use detection systems that require permanent infrastructure and that only detect the presence of the UAS vehicle. Nor can they use jammers to mitigate UAS because of the risk of interfering with emergency aircraft and communications, or the risk of a UAS crashing.